Image forming apparatus and air intake and exhaust system

ABSTRACT

An image forming apparatus includes a dehumidifier in which a dehumidified air flow path and an exhaust heat air flow path are formed. A cooling-and-dehumidifying member is positioned in the dehumidified air flow path and a heat exhaust member is positioned in the exhaust heat air flow path. A case covers an aperture common to the dehumidified air flow path and the exhaust heat air flow path. An imaging unit is connected to the dehumidifier by a connecting air flow path through which dehumidified air is introduced into the imaging unit from the dehumidified air flow path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2004-326745, filed on Nov. 10, 2004, No. 2004-328991, filed on Nov. 12, 2004 and No. 2005-004401, filed on Jan. 11, 2005, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming apparatus equipped with a dehumidifier that dehumidifies the inside of the apparatus.

2. Description of the Related Art

Generally, in a dehumidifier in an image forming apparatus, air in a copying section containing moisture and dusty toner generated in a developing section are guided into a dehumidifier by an air distribution fan. Dew is formed by moisture in the air, turned to droplets, and falls into a recycled water receiver by a cooling fan fitted to a low-temperature section of a Peltier element. At this time, the dusty toner is captured by the droplets, and falls into the recycled water receiver together with the droplets. The air, from which moisture and dusty toner are removed, is exhausted outside of the dehumidifier and supplied to the copying unit. At this time, by cooling a high-temperature section of the Peltier element with the air distribution fan via a radiating fin fitted to the Peltier element, the cooling efficiency of the low-temperature section of the Peltier element increases. Accordingly, the dehumidification efficiency is improved, as disclosed in Japanese Patent Application Laid-Open No. H6-83129, paragraph [0035] to [0036], FIGS. 1 and 2.

The electrophotographic image forming apparatus is apt to be affected by environmental changes, and a measure against a characteristic change due to temperature and humidity becomes a large technical problem. For example, the main characteristics of image processing such as chargeability and toner properties (fluidity and the like) are largely affected by the humidity, causing defective charging, defective cleaning, and the like, thereby becoming a cause of defective image formation. Furthermore, the rigidity and Young's modulus of rubber parts used for a cleaning blade and for transporting and separating paper change according to the temperature, thereby causing defective cleaning, jam, and defective transport such as multi feed and the like. Furthermore, when a transfer material such as paper absorbs moisture, it becomes soft, thereby decreasing the transport property, or when paper becomes dry, the resistance increases, thereby causing defective transfer.

Therefore, an image forming apparatus including a detector that detects the temperature and humidity in the apparatus, and an adjusting unit that adjusts the temperature and humidity in the apparatus based on the detection result of the temperature and humidity detector has been disclosed. For example, Japanese Patent Application Laid-Open No. H9-81018 discloses an image forming apparatus in which the main part thereof is configured substantially as a closed space. The humidity in the apparatus is detected by a humidity detector and compared with a predetermined optimum humidity, and when there is a difference, a humidity adjusting unit adjusts the humidity in the apparatus. Japanese Patent Application Laid-Open No. 2003-280467 discloses an image forming apparatus in which a plurality of imaging units is respectively configured substantially as a closed space, and a temperature and humidity detector and a temperature and humidity adjusting unit are provided for each of the imaging units.

In an assembly process of a conventional dehumidifier, however, since the Peltier element is susceptible to load and impact, difficulties arise when the Peltier element, a cooling-and-dehumidifying member, and a heat exhaust member are uncovered, and the work is complicated.

In the image forming apparatuses disclosed in Japanese Patent Application Laid-Open Nos. H9-81018 and 2003-280467, the position between the temperature and humidity detector and a heat source that generates heat in the apparatus is not taken into consideration. When the temperature and humidity detector is installed near the heat source, for example, a fixing apparatus that fixes a toner image by thermo-compression bonding, the temperature and humidity detector is directly affected by the heat from the heat source. Therefore, even if the temperature and humidity adjusting unit is operated based on the detection result of the temperature and humidity detector, it is difficult to control the ambient atmosphere in the apparatus and the imaging units to a temperature or humidity suitable for image formation.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least solve the problems in the conventional technology.

According to an aspect of the present invention, an image forming apparatus includes a flow path forming member that forms a dehumidified air flow path and an exhaust heat air flow path, a dehumidifier including a cooling-and-dehumidifying member positioned in the dehumidified air flow path, and a heat exhaust member positioned in the exhaust heat air flow path, a case that covers an aperture common to the dehumidified air flow path and the exhaust heat air flow path, and an imaging unit connected to the dehumidifier by a connecting air flow path through which dehumidified air is introduced into the imaging unit from the dehumidified air flow path.

According to another aspect of the present invention, an image forming apparatus includes a flow path forming member that forms a dehumidified air flow path and an exhaust heat air flow path, a dehumidifier including a cooling-and-dehumidifying member positioned in the dehumidified air flow path, a heat exhaust member positioned in the exhaust heat air flow path, and a Peltier element positioned between the cooling-and-dehumidifying member and the heat exhaust member, a case that covers an aperture common to the dehumidified air flow path and the exhaust heat air flow path, and an imaging unit connected to the dehumidifier by a connecting air flow path through which dehumidified air is introduced into the imaging unit from the dehumidified air flow path.

According to still another aspect of the present invention, an air intake and exhaust system includes a flow path forming member that forms a dehumidified air flow path and an exhaust heat air flow path, a dehumidifier including a cooling-and-dehumidifying member positioned in the dehumidified air flow path, and a heat exhaust member positioned in the exhaust heat air flow path, an inlet port to which the dehumidifier is connected, a case that covers an aperture common to the dehumidified air flow path and the exhaust heat air flow path, a connecting air flow path through which dehumidified air is introduced into an imaging unit from the dehumidified air flow path, a dehumidifying fan that sends an air flow from the dehumidified air flow path to the connecting air flow path, and a heat exhaust fan that discharges exhaust heat from the exhaust heat air flow path to outside.

According to still another aspect of the present invention, an air intake and exhaust system includes a flow path forming member that forms a dehumidified air flow path and an exhaust heat air flow path, a dehumidifier including a cooling-and-dehumidifying member positioned in the dehumidified air flow path, a heat exhaust member positioned in the exhaust heat air flow path, and a Peltier element positioned between the cooling-and-dehumidifying member and the heat exhaust member, an inlet port to which the dehumidifier is connected, a case that covers an aperture common to the dehumidified air flow path and the exhaust heat air flow path, a connecting air flow path through which dehumidified air is introduced into an imaging unit from the dehumidified air flow path, a dehumidifying fan that sends an air flow from the dehumidified air flow path to the connecting air flow path, and a heat exhaust fan that discharges exhaust heat from the exhaust heat air flow path to outside.

According to still another aspect of the present invention, an image forming apparatus includes a plurality of imaging units that forms a toner image on an image carrier, a temperature/humidity detector that detects temperature and humidity in the image forming apparatus, a temperature/humidity adjusting unit that adjusts temperature and humidity in the image forming apparatus, a controller that controls the temperature/humidity adjusting unit based on a detection result of the temperature/humidity detector to adjust temperature and humidity to a predetermined range, and a heat source that generates highest temperature in the image forming apparatus, wherein the temperature/humidity detector is located near one of the imaging units located furthest from the heat source.

According to still another aspect of the present invention, an image forming apparatus includes a plurality of imaging units that forms a toner image on an image carrier, a temperature/humidity detector that detects temperature and humidity in each of the imaging units, a temperature/humidity adjusting unit that adjusts temperature and humidity in each of the imaging units, a controller that controls the temperature/humidity adjusting unit based on a detection result of the temperature/humidity detector to adjust temperature and humidity to a predetermined range, and a heat source that generates highest temperature in the image forming apparatus, wherein the temperature/humidity detector is located in one of the imaging units located furthest from the heat source.

The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a block diagram of an image forming apparatus according to a first embodiment of the present invention;

FIG. 2 is a perspective view of a dehumidifier used in the first embodiment;

FIG. 3 is a perspective view of the dehumidifier used in the first embodiment;

FIG. 4 is a plan view of the dehumidifier used in the first embodiment;

FIG. 5 is a plan view of a dehumidifier used in the second embodiment;

FIG. 6 is a plan view of a dehumidifier used in the third embodiment;

FIG. 7 is a plan view of another example of the dehumidifier used in the third embodiment;

FIG. 8 is a perspective view of an image forming apparatus according to a fourth embodiment of the present invention, with a part of the configuration being shown in broken-out-section;

FIG. 9 is a flowchart of an operation performed by the dehumidifier of the present invention;

FIG. 10 is a schematic block diagram of the inner configuration of a printer according to a fifth embodiment of the present invention;

FIG. 11 is a control block diagram of the printer;

FIG. 12 is a schematic block diagram of the inner configuration of a printer according to another embodiment;

FIG. 13 depicts the configuration of a desiccant air conditioner;

FIG. 14 depicts the configuration of an air conditioner using a Peltier element; and

FIG. 15 is a characteristic diagram of the relation between temperature and saturated water vapor content.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention will be described below with reference to accompanying drawings. The present invention is not limited to these embodiments.

FIGS. 1 to 4 depict a first embodiment of the present invention. In FIGS. 1 to 4, like or equivalent elements are designated with like or similar reference numerals, and redundant explanations thereof are omitted.

FIG. 1 is a block diagram of the principle of an image forming apparatus according to the first embodiment of the present invention. An image forming apparatus 1 includes a dehumidifier 13 having a Peltier element 10 arranged between a cooling-and-dehumidifying member 11 and an heat exhaust member 12, a dehumidifier/exhaust heat case 15 that integrally covers a common aperture of a dehumidified air flow path A provided on a side of the cooling-and-dehumidifying member 11 and an exhaust heat air flow path B provided on a side of the heat exhaust member 12, and an electrophotographic imaging unit 14 connected to a subsequent stage of the dehumidifier 13 for introducing dehumidified air C from the dehumidified air flow path A through an air flow path 24.

The image forming apparatus 1 includes an inlet port 16, the dehumidifier 13 connected to the inlet port 16, the air flow path 24 located on a downstream side of the dehumidifier 13, the imaging unit 14 connected to the air flow path 24, an exhaust path 23 located on a downstream side of the imaging unit 14, and an exhaust port 17 located at the end of the exhaust path 23.

The dehumidifier 13 includes a dehumidifying fan 21, the cooling-and-dehumidifying member 11 in a form of a fin located on a discharge side of the dehumidifying fan 21 for increasing the contact area with the air, the heat exhaust member 12 in a form of a fin located on a downstream side of the inlet port 16 for increasing the contact area with the air, and a heat exhaust fan 20 located on a downstream side of the heat exhaust member 12.

The imaging unit 14 is located between the air flow path 24 and the exhaust path 23, and includes a humidity detector 8 that detects the humidity inside the apparatus, a transfer paper container 26 for receiving transfer paper 28, a transfer paper transport unit 29, a drum-like photoconductor 31, and an image transfer unit 32 that transfers an image onto the photoconductor 31. The humidity detector 8 detects the relative humidity in the imaging unit 14, and when the detected humidity indicates a predetermined value or higher, dehumidifies the air in the dehumidifier/exhaust heat case 15 by operating predetermined equipment arranged in the dehumidifier/exhaust heat case 15, to supply dehumidified air from the dehumidifier/exhaust heat case 15 to the imaging unit 14. The function and the like of the humidity detector 8 are explained later in detail.

In the image forming apparatus 1, an exhaust-heat foreign-matter removing member 19 can be provided on an inlet port side of the heat exhaust fan 20 provided in the dehumidifier 13, as a dustproof measure. A dehumidification foreign-matter removing member 18 can be provided inside of the air flow path 24, as well. In the first embodiment, to enable stable operation of the imaging unit 14 and prevent an abnormal image, a unit that attracts fine particles in the air by a fine particles-removing filter or a static elimination filter can be appropriately used.

An air intake and exhaust system includes the inlet port 16 for drawing the air in, the dehumidifier 13 having the Peltier element 10 arranged between the cooling-and-dehumidifying member 11 and the heat exhaust member 12, the dehumidifier/exhaust heat case 15 that integrally covers the common aperture of the dehumidified air flow path A provided on a side of the cooling-and-dehumidifying member 11 and the exhaust heat air flow path B provided on the side of the heat exhaust member 12, the air flow path 24 for allowing the dehumidified air C to pass from the dehumidified air flow path A to the imaging unit 14, and the heat exhaust fan 20 for exhausting exhaust heat D from the exhaust heat air flow path B. In FIG. 1, reference letter E represents exhaust air from the imaging unit 14.

FIG. 2 is a perspective view of the dehumidifier 13 used in the image forming apparatus according to the first embodiment. Overlapping explanations for like members as in FIG. 1 are omitted.

The dehumidifier 13 includes the dehumidifier/exhaust heat case 15 that is located in an area enclosed by a two-dot chain line, and integrally covers the common aperture of the dehumidified air flow path A and the exhaust heat air flow path B enclosed by a housing 22. An insulating member 9 that increases the dehumidification effect can be provided at a corner on the back of the dehumidifier/exhaust heat case 15.

The dehumidifier 13 is provided with an exhaust port 17 a on the left side of the front face, and can exhaust the exhaust air exhausted by the heat exhaust fan 20. A water absorption/diffusion member 25 is provided respectively on a bottom face and a vertical surface between the exhaust port 17 a and the heat exhaust fan 20, so that droplets generated by dewing from the moisture in the air cooled by the cooling-and-dehumidifying member 11 (see FIG. 1) can be allowed to infiltrate in the water absorption/diffusion member 25.

The dehumidifier 13 is provided with the inlet port 16 on the right of the front face, and can introduce the air through a dehumidification foreign-matter removing member 18 a covering the inlet port 16 to execute dust-proof measures.

FIG. 3 is a perspective view of the dehumidifier 13 used in the image forming apparatus according to the first embodiment. The dehumidifier/exhaust heat case 15 (see FIG. 1) is removed from the housing 22. Overlapping explanations for like members as in FIG. 2 are omitted.

The dehumidifier 13 includes an inlet port 16 b located on the front face of the dehumidifying fan 21, the inlet port 16 b separated from the dehumidifying fan 21, the water absorption/diffusion member 25 located near the inlet port 16 a, the exhaust-heat foreign-matter removing member 19 provided at an inlet port of the heat exhaust fan 20, and a plurality of the cooling-and-dehumidifying members 11 located on the downstream of the dehumidifying fan 21.

The cooling-and-dehumidifying members 11 has an opening formed substantially at the center of a wall, which separates air flow drawn in by a negative pressure by the heat exhaust fan 20, and air flow pressurized by the dehumidifying fan 21, and can improve the dehumidification effect and the heat exhaust effect.

The operation of the image forming apparatus 1 is explained with reference to FIG. 1 and FIG. 4. In the image forming apparatus 1, the air drawn in from the dehumidified air flow path A is dehumidified by the cooling-and-dehumidifying member 11, and the dehumidified air is fed to the imaging unit 14 through the inner air flow path 24.

The dehumidifier 13 feeds the dehumidified air to the imaging unit 14, to reduce changes in the characteristic values (hardness, Young's modulus, and the like) of rubber parts, changes in electric charges of a developer, and changes in toner properties (fluidity and the like), and hence, can provide a system having a stable imaging function. Furthermore, occurrence of abnormal images such as image blur occurring under a high humidity condition can be suppressed.

In this example, the humidity detector 8 is fitted to an imaging unit (developing unit) 33 d (see FIG. 8) in the imaging unit 14 (see FIG. 1). The humidity detector 8 is for detecting the humidity in the imaging unit, and can be also used at the time of process control. Alternatively, a temperature/humidity detector can be used.

The dehumidifier 13 operates, as shown in a flowchart shown in FIG. 9, when the humidity detector 8 indicates relative humidity of 60% or higher. More specifically, when the humidity detector 8 indicates relative humidity of 60% or higher, the dehumidifying fan 21 (heat-absorbing fan), the Peltier element 10, and the heat exhaust fan 20 (radiating fan) are energized, and the outside air is introduced, respectively, to the dehumidified air flow path A by the dehumidifying fan 21 (heat-absorbing fan), and to the exhaust heat air flow path B by the heat exhaust fan 20 (radiating fan). The outside air introduced to the dehumidified air flow path A is dehumidified by the cooling-and-dehumidifying member 11, cooled by the Peltier element 10 to turn into the dehumidified air. C, and fed to the imaging unit 14 through the air flow path 24. The outside air introduced to the exhaust heat air flow path B is heated by the heat from the heat exhaust member 12, heated by the Peltier element 10, absorbs water vapor evapotranspirated by the water absorption/diffusion member 25 to turn into exhaust heat D, and is exhausted from the exhaust port 17.

When the humidity in the imaging unit 14 reaches a certain value, the dehumidifier 13 is operated as shown in FIG. 9. Accordingly, the humidity in the imaging unit 14 can be maintained at a certain value or less, thereby realizing a stable image quality. Furthermore, by operating the dehumidifier 13 only when the humidity detector 8 indicates a certain humidity, energy saving can be realized. In addition, various sensors in the imaging unit 14 can be cleaned by the wind pressure of the air fed to the imaging unit 14, to improve the detection accuracy.

To operate the dehumidifier 13, much power is required. On the other hand, in the state that paper is fed to the image forming apparatus 1, the influence of the humidity with respect to the imaging unit 14 is small. Therefore, by operating the dehumidifier 13 only in the state that paper is not fed to the imaging unit 14, power consumed by the whole image forming apparatus 1 can be suppressed. Furthermore, when a user wishes to save energy, the dehumidifier 13 can be left inactivated completely.

The dehumidifier 13 has the Peltier element 10, the cooling-and-dehumidifying member 11, and the heat exhaust member 12, and can be covered and integrally formed with the housing 22 and the dehumidifier/exhaust heat case 15 that form the dehumidified air flow path A and the exhaust heat air flow path B. An insulating member 9 a shown in FIG. 4 insulates the dehumidified air flow from the inner temperature of the image forming apparatus 1, to increase the dehumidification effect.

By using the Peltier element 10 in the dehumidifier 13, the apparatus can be downsized and energy saving can be realized. For example, the apparatus is made small and simplified by using the Peltier element 10 shown in FIG. 4.

In the dehumidifier 13, the cooling-and-dehumidifying member 11 is a cooling fin, and a heat-conduction member (not shown) is clamped between the heat absorbing surface of the Peltier element 10 and the dehumidifier 13. Likewise, the heat exhaust member 12 here is a radiating fin, and a heat-conduction member (not shown) is clamped between the heat generating surface of the Peltier element 10 and the dehumidifier 13.

An insulating member 9 b is provided at an opening of a wall, which separates the dehumidified air flow path A from the exhaust heat air flow path B, and serves as an insulating member that insulates between the cooling-and-dehumidifying member 11 (cooling fin) and the heat exhaust member 12 (radiating fin).

The housing 22 forms a part of the dehumidified air flow path A and the exhaust heat air flow path B surrounding the dehumidifier 13, and the common aperture of the dehumidified air flow path A and the exhaust heat air flow path B is exposed. The common aperture is integrally covered with the dehumidifier/exhaust heat case 15, thereby providing the dehumidified air flow path A and the exhaust heat air flow path B, to separate the air flow. The water absorption/diffusion member 25 absorbs and transports dehumidified water generated in the cooling-and-dehumidifying member 11.

The dehumidifying fan 21 serves as a fan for feeding air to the cooling-and-dehumidifying member 11, and sends dehumidified air from the dehumidified air flow path to the air flow path 24. On the other hand, the heat exhaust fan 20 absorbs air from the heat exhaust member 12 and exhausts heated air.

As shown in FIG. 4, the water absorption/diffusion member 25 can absorb dehumidified water dropped from the cooling-and-dehumidifying member 11, and transport water horizontally. That is, since the water absorption/diffusion member 25 horizontally transports water formed by dewing in the cooling-and-dehumidifying member 11 at any time, it is not necessary to provide a reservoir for collecting a large amount of water below the cooling-and-dehumidifying member 11, and hence, water leak due to an influence of the image forming apparatus 1 being vibrated or inclined can be prevented.

Furthermore, a reservoir area for collecting dehumidified water can be provided side by side in the dehumidifier 13, so as to collect water formed by dewing temporarily. That is, by providing a reservoir area in the dehumidifier 13, dehumidified water generated in the cooling-and-dehumidifying member 11 can be collected as it is in the dehumidifier 13.

Since the water absorption/diffusion member 25 is installed on the bottom face and the vertical surface along the exhaust heat air flow path B, the absorbed water can be easily evaporated even in a space-saving area. Particularly, since the air flow after having passed the heat exhaust member 12 is warm air as compared to the air flow at the inlet port, the evaporation ability of water absorbed by the water absorption/diffusion member 25 can be improved.

Thus, since the dehumidifier 13 has an evaporative mechanism of the dehumidified water, the maintenance property of the dehumidifier and the downsizing effect can be improved. By evaporating the dehumidified water in the exhaust heat air flow path, a water storage tank having a large capacity, a disposal operation of water, and the like are not required.

In the image forming apparatus 1, the area of the imaging unit 14 to be dehumidified is set to be the vicinity of the photoconductor 31 and other process units adjacent thereto (for example, the transfer paper container 26, the transfer paper transport unit 29, and the image transfer unit 32), thereby promoting downsizing and energy saving.

Furthermore, by providing the imaging unit 14 in a substantially closed process cartridge including the photoconductor 31 and at least one other process unit (for example, the image transfer unit 32), the dehumidification efficiency can be increased, thereby enhancing downsizing and energy saving of the image forming apparatus 1.

Furthermore, if the area to be dehumidified is extended up to the vicinity of the area including the transfer paper 28 and the transfer paper transport unit 29 and to the inside of the transfer paper container 26, the transfer paper 28 and the transfer paper transport unit 29 are prevented from absorbing moisture excessively as compared to the atmosphere, thereby providing stable transportability and transferability. Furthermore, since the exhaust-heat foreign-matter removing member 19 is provided in the exhaust heat air flow path B or the dehumidification foreign-matter removing member 18 is provided in the dehumidified air flow path A, even if there is foreign matter such as dust in the outside air, the parts in the air-conditioned area in the image forming apparatus 1 can be effectively prevented from being soiled.

Thus, in the first embodiment, the imaging system can be stabilized by temperature control performed by dehumidifying the air in the dehumidified air flow path, and occurrence of abnormal images in a high-temperature environment can be also prevented by dehumidifying the air in the image forming apparatus 1. By adopting the configuration of a monolithic dehumidifier 13 covered with the dehumidifier/exhaust heat case 15, an image forming apparatus in which the dehumidified air and the exhaust air are not mixed together can be provided.

Since the image forming apparatus 1 includes the monolithic dehumidifier 13 covered with the dehumidifier/exhaust heat case 15, unbalanced load and impact with respect to the Peltier element 10 can be effectively prevented in a process of assembling the dehumidifier 13 in the image forming apparatus 1.

Furthermore, by adopting the monolithic dehumidifier 13 including the heat exhaust fan 20 covered with the dehumidifier/exhaust heat case 15, gaps and joints in the exhaust path between the heat exhaust member 12 and the heat exhaust fan 20 can be reduced. Accordingly, the heat in the dehumidifier 13 can be exhausted efficiently, and the dehumidification efficiency can be also improved.

Since the dehumidifying fan 21 is integrally formed with the dehumidifier 13, gaps and joints in the exhaust path between the heat exhaust member 12 and the heat exhaust fan 20 is reduced, and hence, the air can be efficiently dehumidified.

Since the dehumidifying fan 21 pressurizes the outside air and sends the air to be dehumidified to the dehumidifier 13, it is not necessary to provide an imaging unit air flow fan, thereby enabling reduction in the number of parts of the image forming apparatus 1. Even if there is foreign matter such as dust in the outside air, the dehumidification foreign-matter removing member 18 or the exhaust-heat foreign-matter removing member 19 removes the foreign matter. Accordingly, the internal parts in the image forming apparatus 1 can be prevented from being soiled.

That is, by providing the foreign matter removing member in each air flow path, even if there is foreign matter such as dust in the outside air, the parts in the air-conditioned area can be prevented from being soiled. Furthermore, since the respective foreign matter removing members are integrally formed with the dehumidifier 13 and there is little gap in the respective air flow paths, the inner parts in the image forming apparatus 1 can be effectively prevented from being soiled.

By making the imaging unit 14 substantially closed, natural exchange with the air outside the image forming apparatus 1 is reduced, thereby improving the dehumidification effect. Furthermore, since the dehumidification efficiency is improved, energy consumption can be reduced.

By performing dehumidification with respect to a limited area, that is, the photoconductor and the process units adjacent thereto, which have a large dehumidification effect, the dehumidification efficiency is improved, thereby enabling downsizing and energy saving.

Furthermore, by integrally forming the area to be dehumidified as a process cartridge, the closed condition of the area to be dehumidified can be easily maintained, to increase the dehumidification efficiency, thereby enabling downsizing and energy saving of the image forming apparatus 1.

Furthermore, by expanding the area to be dehumidified up to the vicinity of the area including the transfer paper 28 and the transfer paper transport unit 29 and to the inside of the transfer paper container 26, the transfer paper 28 and the transfer paper transport unit 29 are prevented from absorbing moisture excessively, thereby improving stable transportability and transferability of the transfer paper 28.

FIG. 5 is a plan view of a dehumidifier used in the image forming apparatus according to a second embodiment of the present invention. Overlapping explanations of like elements in the dehumidifier shown in FIG. 4 are omitted.

The air pressurized and fed from the dehumidified air flow path shown on the right side of FIG. 5 is transferred to the air flow path 24 (see FIG. 1) on the downstream side, through the cooling-and-dehumidifying member 11. Dust mixed in the air introduced from the outside is filtered by the dehumidification foreign-matter removing member 18 arranged between the cooling-and-dehumidifying member 11 and the air flow path 24, thereby preventing contamination of the photoconductor 31 and the like.

FIGS. 6 and 7 are plan views of the dehumidifier used in an image forming apparatus according to a third embodiment of the present invention. Overlapping explanations of like elements in the dehumidifier shown in FIG. 4 are omitted.

The air pressurized and fed from the dehumidified air flow path shown on the right side of FIG. 6 is transferred to the air flow path 24 (see FIG. 1) on the downstream side, through the cooling-and-dehumidifying member 11. Dust mixed in the air introduced from the outside is filtered by a common foreign matter removing member 27 arranged between the cooling-and-dehumidifying member 11 and the air flow path 24, thereby preventing contamination of the photoconductor 31 and the like.

The common foreign matter removing member 27 is inserted into a through opening provided in the wall separating the dehumidified air flow path and the exhaust heat air flow path, and extended to the discharge opening side of the heat exhaust fan 20. In this case, the common foreign matter removing member 27 can effectively remove the dust mixed in the exhaust heat air flow passing through the exhaust heat air flow path, thereby preventing deterioration in the durability or the required performance of the dust-proof parts in the image forming apparatus 1.

FIG. 7 is a plan view of a modified example of the third embodiment. The common foreign matter removing member 27 is provided near the heat exhaust fan 20 in FIG. 6. However, in the modified example shown in FIG. 7, a common foreign matter removing member 27 a is arranged between the dehumidifying fan 21 and the cooling-and-dehumidifying member 11.

Since the common foreign matter removing member 27 a is located on the upstream of the exhaust heat air flow path and the dehumidified air flow path, the foreign matter mixed in the absorbed air can be removed at an early stage. Accordingly, such a problem that dust adheres on the fins in the cooling-and-dehumidifying member 11 and the heat exhaust member 12 can be effectively prevented.

Thus, in the third embodiment, since the dehumidification foreign-matter removing member and the exhaust-heat foreign-matter removing member are constructed as one part, the number of parts can be reduced, thereby reducing the number of processes in the maintenance work.

FIG. 8 is a perspective view of an image forming apparatus according to a fourth embodiment of the present invention, with a part of the configuration being cut. Overlapping explanations of like elements shown in FIG. 1 are omitted.

The image forming apparatus 1 includes the dehumidifier 13 having the inlet port 16 and the exhaust port 17 a, a plurality of imaging units 14 a to 14 d connected to the dehumidifier 13 via the air flow path 24, and an exhaust port 17 b that exhausts exhaust air from the imaging units 14 a to 14 d via the exhaust path.

The imaging units 14 a to 14 d includes photoconductors 31 a to 31 d that transfer primary color images respectively different from each other, image transfer units 32 a to 32 d, developing units 33 a to 33 d, cleaning units 34 a to 34 d, and toner supply units 35 a to 35 d.

The imaging units 14 a to 14 d can provide a color imaging system having photoconductors 31 a to 31 d, to which dehumidified air is supplied from the dehumidifier 13, with the foreign matter therein being removed.

In the fourth embodiment, since the air in the dehumidified air flow path is dehumidified, changes in the characteristic values (hardness, Young's modulus, and the like) of rubber parts in the image forming apparatus 1, changes in electric charges of the developer, and changes in toner properties (fluidity and the like) can be reduced. Accordingly, in the color imaging system having the photoconductors 31 a to 31 d, a difference in the transferred images of the respective imaging systems can be reduced, and out of color registration can be reduced, thereby achieving high quality of images.

The action and effects described in the above embodiments are only the most suitable ones achieved by the invention, and are not limited to those described in the embodiments.

A fifth embodiment in which the present invention is applied to a full color printer (hereinafter, “printer”), which is the image forming apparatus, is explained. FIG. 10 is a schematic block diagram of the inner configuration of the printer. As shown in FIG. 10, the printer includes process cartridges 102Y, 102C, 102M, and 102K, which are the imaging units for imaging respective color toner images of yellow (Y), cyan (C), magenta (M), and black (K), in an apparatus body 101. Hereinafter, subscripts Y, C, M, and K at the end of respective reference numbers indicate that these are members for yellow, cyan, magenta, and black. An intermediate transfer unit 104 having an intermediate transfer belt 103, to which toner images formed by the respective process cartridges 102 are transferred, is provided below the respective process cartridges 102. Below the intermediate transfer unit 104, a fixing apparatus 105, which is the fixing unit that fixes the toner image on the transfer paper P, and a transport unit 106 that transports the transfer paper P to the fixing apparatus are provided. The fixing apparatus 105 includes a heating roller 105 a having a heat source (not shown) therein, and a pressure roller 105 b pressed against the heating roller 105 a, and hence, the fixing apparatus 105 is a heat source that generates heat most in the apparatus. A paper feed cassette 107 for storing the transfer paper P, which can be pulled out, is provided in the lower part of the apparatus body 101.

The respective process cartridges 102Y, 102C, 102M, and 102K respectively include a drum-like photoconductor 110Y, 110C, 110M, or 110K, a charging roller 111, 111C, 111M, or 111K that charges the photoconductor 110, a development apparatus 112Y, 112C, 112M, or 112K that develops a latent image formed on the photoconductor 110, and a cleaning blade 113Y, 113C, 113M, or 113K that cleans residual toner on the photoconductor 110. Furthermore, the respective process cartridges 102Y, 102C, 102M, and 102K respectively include an optical unit (not shown) that can irradiate laser beams to the photoconductor 110Y, 110C, 110M, or 110K.

The process for obtaining a color image in the printer having such a configuration is explained. At first, in the process cartridge 102Y, 102C, 102M, 102K, the photoconductor 110Y, 110C, 110M, 110K is uniformly charged by the charging roller 111Y, 111C, 111M, 111K. Thereafter, the laser beams are scanned and exposed by the optical unit based on the image information, to form a latent image on the surface of the photoconductor 110Y, 110C, 110M, 110K. The latent image on the photoconductor 110Y, 110C, 110M, 110K is developed by the respective color toners carried on the developing roller in the development apparatus 112Y, 112C, 112M, 112K, to become a visible image as a toner image. The toner images on the photoconductors 110Y, 110C, 110M, and 110K are sequentially overlapped and transferred onto the intermediate transfer belt 103. On the other hand, the transfer paper P in the paper feed cassette 107 is transported into the apparatus body 101 by a paper feed roller 108 arranged near the paper feed cassette 107, and transported to a secondary transfer unit at predetermined timing by a resist roller pair 109. In the secondary transfer unit, the toner image formed on the intermediate transfer belt 103 is transferred onto the transfer paper P. The transfer paper P onto which the toner image is transferred is transported by the transport unit 106, passes between the heating roller 105 a and the pressure roller 105 b in the fixing apparatus 105, thereby performing image fixation, and the transfer paper P is ejected outside of the apparatus body.

In the printer according to the fifth embodiment, a temperature/humidity detector 120, which is the temperature/humidity detector that detects temperature and humidity in the apparatus body 101, is provided above the black process cartridge 102K, which is located at the furthest position from the fixing apparatus 105 as the heat source, among the process cartridges 102Y, 102C, 102M, and 102K. In the upper part of the apparatus body 101, an air conditioner 121 is provided, which is the temperature/humidity adjusting unit that adjusts the temperature and humidity in the ambient atmosphere in the apparatus body 101.

As shown in FIG. 11, a controller 122 that controls the operation of the air conditioner 121 based on the detection result of the temperature/humidity detector 120 so that the temperature and the humidity in the apparatus body 101 is within a predetermined range is installed. The controller 122 reads the temperature detected by the temperature/humidity detector at predetermined timing, to determine whether the detected temperature is within the predetermined range. When the detected temperature is within the predetermined range, the controller 122 stops the operation of the air conditioner 121. When the detected temperature is not within the predetermined range, the controller 122 operates the air conditioner 121 so as to control the temperature and humidity in the apparatus body 101 to be within the predetermined range. The controller 122 can be provided exclusively for the control of the air conditioner 121, or can be a controller that can control the whole image forming process. A part to be air-conditioned by the air conditioner 121 is desirably formed substantially in a closed configuration. While the part to be air-conditioned is the entire part of the apparatus body 101, the configuration can be such that each process cartridge 102Y, 102C, 102M, 102K that is most likely to be affected by the temperature and humidity can be individually air-conditioned.

FIG. 12 is a schematic block diagram of the inner configuration of a printer according to another embodiment. In FIG. 12, like parts as in FIG. 10 are denoted by like reference signs, and the explanation thereof is omitted. As shown in FIG. 12, a temperature/humidity detector 123, which is the temperature/humidity detector that detects temperature and humidity in the process cartridge 102, can be provided above the black process cartridge 102K, which is located at the furthest position from the fixing apparatus 105, among the process cartridges 102Y, 102C, 102M, and 102K. In the upper part of the apparatus body 101, an air conditioner 124 is provided, which is the temperature/humidity adjusting unit that adjusts the temperature and humidity in the ambient atmosphere in the process cartridges 102Y, 102C, 102M, and 102K. Also in this case, the controller 122 reads the temperature detected by the temperature/humidity detector 123 at predetermined timing, to determine whether the detected temperature is within the predetermined range. When the detected temperature is within the predetermined range, the controller 122 stops the operation of the air conditioner 124. When the detected temperature is not within the predetermined range, the controller 122 operates the air conditioner 124 so as to control the temperature and humidity in the process cartridges 102Y, 102C, 102M, and 102K to be within the predetermined range.

The process cartridges 102Y, 102C, 102M, and 102K, which are the part to be air-conditioned by the air conditioner 124 is desirably formed substantially in a closed configuration. For example, the configuration is such that a part of a side plate of the process cartridge 102, which is the incident range of the laser beams from the optical unit, is formed of a transparent window, and only the secondary transfer unit for transferring the toner image on the photoconductor 110 onto the transfer material is opened. An inlet port and an exhaust port connected to the air conditioner 124 are then formed in the process cartridge 102.

For the air conditioners 121 and 124, a desiccant air conditioner or an air conditioner using a Peltier element can be used. FIG. 13 depicts the configuration of the desiccant air conditioner. As shown in FIG. 13, a desiccant air conditioner 130 includes a desiccant rotor 131 rotating in a direction of arrow A, a heater 132, and a fan 133. In the lower part of the desiccant rotor 131, conditioned air from a part to be air-conditioned passes from a direction of arrow B, and at this time, moisture is absorbed by the desiccant rotor 131 and passes in a direction of arrow C, and dried conditioned air is supplied by the fan 133 in a direction of arrow D, to be returned to the part to be air-conditioned. On the other hand, in the upper part of the desiccant rotor 131, moisture in the desiccant rotor 131 is removed by the heater 132, and high moisture is discharged in a direction of arrow E toward a radiator or the outside of the apparatus. The desiccant air conditioner 130 can realize a small size and low noise, as compared to an air conditioner using a compressor.

FIG. 14 depicts the configuration of an air conditioner using the Peltier element. As shown in FIG. 14, an air conditioner 140 using the Peltier element is configured such that a Peltier element 141, whose one surface becomes low temperature and the other surface becomes high temperature according to the flowing direction of the electric current is put between heat exchanger plates of a fin unit 142 on the heat absorbing side and a fin unit 143 on the heat generating side. In the fin unit 142 on the heat absorbing side, the conditioned air is allowed to flow in a direction of arrow F and cooled by a fan 144, and the moisture is removed as dew condensation. In the fin unit 143 on the heat generating side, the heated conditioned air is cooled by a fan 146. The air conditioner 140 using the Peltier element 141 can realize a small size and low noise, as compared to an air conditioner using a compressor.

While the temperature/humidity detectors 120 and 123 preferably detect both temperature and humidity individually, at least one of temperature and humidity need only to be detected. Also, in the air conditioners 121 and 124, while it is preferable that both temperature and humidity can be individually controlled, at least one of temperature and humidity need only to be controlled. For example, the relation between the temperature and saturated water vapor content is as shown in FIG. 15. Therefore, for example, the saturated water vapor content at 40° C. is 51.2 g/m², and at this time, if the water vapor content is 11.4 g/m², the relative humidity becomes 11.2/51.2×100%=22%. When the temperature is 25° C., the saturated water vapor content is 22.8 g/m², and the relative humidity becomes 11.4/22.8×100%=50%. Accordingly, by controlling the temperature, the humidity can be controlled.

In the printer according to the fifth embodiment, the temperature/humidity detector 120 is installed near the black process cartridge 120K located at the furthest position from the fixing apparatus 105, among the process cartridges 102Y, 102C, 102M, and 102K. Therefore, the temperature/humidity detector 120 can detect temperature and humidity in the ambient atmosphere in the apparatus body 101, in the state that the temperature/humidity detector 120 is hardly affected directly by the heat from the fixing apparatus 105, as compared to an instance in which the temperature/humidity detector 120 is installed near the process cartridge 102Y, 102C, or 102M.

In the printer according to the fifth embodiment, the temperature/humidity detector 123 is installed in the black process cartridge 102K located at the furthest position from the fixing apparatus 105, among the process cartridges 102Y, 102C, 102M, and 102K. Since parts in the printer that are apt to be affected by temperature and humidity are provided in the process cartridge 102 in a centralized manner, it is required to detect accurately the temperature and humidity in the ambient atmosphere in the process cartridge 102. When the temperature/humidity detector 123 is installed in the process cartridge 102K, the temperature and humidity in the ambient atmosphere in the process cartridge 102K can be detected more accurately, than in the instance in which the temperature/humidity detector 123 is installed outside the process cartridge 102K.

Furthermore, in the process cartridge 102 having the photoconductor 110, which performs development, charging, and cleaning, the influence of humidity is large, and hence, it is desired to control the humidity (relative humidity) to be equal to or lower than a certain value. In the black process cartridge 102K located at the furthest position from the fixing apparatus 105, if the relative humidity can be set equal to or lower than the certain value, in the process cartridges 102Y, 102C, and 102M close to the fixing apparatus 105, the relative humidity becomes lower than that of the black process cartridge 102K, due to the heat from the fixing apparatus 105. In other words, if the relative humidity is controlled in the black process cartridge 102K located at the furthest position from the fixing apparatus 105, the relative humidity is inevitably maintained to be equal to or lower than the certain value in the other process cartridges 102Y, 102C, and 102M. Accordingly, it is not necessary to install the temperature/humidity detector 120 or 123 in the respective process cartridges 102Y, 102C, and 102M, and only one temperature/humidity detector 120 or 123 can serve the function.

By making the color of the process cartridge located at the furthest position from the heat source black, the temperature and humidity of the black process cartridge 102K having the highest use frequency can be controlled most accurately.

In general, the part generating heat most in the printer is the fixing apparatus that performs fixation by thermo compression bonding. Therefore, by installing the temperature/humidity detector 120, 123 at a position away from the fixing apparatus 105, the temperature/humidity detector 120, 123 is hardly affected by the heat from the fixing apparatus 105.

The desiccant air conditioner 130 and the air conditioner 140 using the Peltier element can realize a small size and low noise, as compared to the air conditioner using a compressor.

Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth. 

1. An image forming apparatus comprising: a flow path forming member that forms a dehumidified air flow path and an exhaust heat air flow path; a dehumidifier including a cooling-and-dehumidifying member positioned in the dehumidified air flow path, and a heat exhaust member positioned in the exhaust heat air flow path; a case that covers an aperture common to the dehumidified air flow path and the exhaust heat air flow path; and an imaging unit connected to the dehumidifier by a connecting air flow path through which dehumidified air is introduced into the imaging unit from the dehumidified air flow path.
 2. The image forming apparatus according to claim 1, wherein the dehumidifier includes a heat exhaust fan that discharges exhaust heat from the exhaust heat air flow path to outside of the image forming apparatus.
 3. The image forming apparatus according to claim 1, wherein the dehumidifier includes a dehumidifying fan provided in front of the cooling-and-dehumidifying member.
 4. The image forming apparatus according to claim 1, wherein the connecting air flow path includes a member that filters out foreign particles.
 5. The image forming apparatus according to claim 1, wherein the exhaust heat air flow path includes a member that filters out foreign particles.
 6. The image forming apparatus according to claim 1, wherein the dehumidifier includes a member that filters out foreign particles from both the dehumidified air flow path and the exhaust heat air flow path.
 7. The image forming apparatus according to claim 1, wherein the exhaust heat air flow path includes an absorption/diffusion member that stores therein dehumidified water.
 8. The image forming apparatus according to claim 1, wherein the imaging unit includes a photoconductor and an image transfer unit adjacent to the photoconductor.
 9. The image forming apparatus according to claim 1, wherein the imaging unit is a process cartridge in which a photoconductor and an image transfer unit adjacent to the photoconductor are integrally combined.
 10. The image forming apparatus according to claim 1, wherein the imaging unit includes transfer paper, a transfer paper transport unit, and a transfer paper container.
 11. The image forming apparatus according to claim 1, wherein the imaging unit includes a color imaging mechanism having independent photoconductors.
 12. The image forming apparatus according to claim 1, wherein the imaging unit includes a humidity detector that detects a relative humidity in the imaging unit, wherein the dehumidifier dehumidifies air in the dehumidified air flow path when the humidity detected by the humidity detector is a predetermined value or more and supplies dehumidified air to the imaging unit from the case.
 13. The image forming apparatus according to claim 4, wherein the imaging unit includes a dust-proof construction in which the dehumidified air introduced from the connecting air flow path is discharged to a downstream exhaust path.
 14. An image forming apparatus comprising: a flow path forming member that forms a dehumidified air flow path and an exhaust heat air flow path; a dehumidifier including a cooling-and-dehumidifying member positioned in the dehumidified air flow path, a heat exhaust member positioned in the exhaust heat air flow path, and a Peltier element positioned between the cooling-and-dehumidifying member and the heat exhaust member; a case that covers an aperture common to the dehumidified air flow path and the exhaust heat air flow path; and an imaging unit connected to the dehumidifier by a connecting air flow path through which dehumidified air is introduced into the imaging unit from the dehumidified air flow path.
 15. The image forming apparatus according to claim 14, wherein the dehumidifier includes a heat exhaust fan that discharges exhaust heat from the exhaust heat air flow path to outside of the image forming apparatus.
 16. The image forming apparatus according to claim 14, wherein the dehumidifier includes a dehumidifying fan provided in front of the cooling-and-dehumidifying member.
 17. The image forming apparatus according to claim 16, wherein the dehumidified air sent from the dehumidifying fan is introduced to the imaging unit through the cooling-and-dehumidifying member.
 18. The image forming apparatus according to claim 14, wherein the connecting air flow path includes a member that filters out foreign particles.
 19. The image forming apparatus according to claim 14, wherein the exhaust heat air flow path includes a member that filters out foreign particles.
 20. The image forming apparatus according to claim 14, wherein the dehumidifier includes a member that filters out foreign particles from both the dehumidified air flow path and the exhaust heat air flow path.
 21. The image forming apparatus according to claim 14, wherein the exhaust heat air flow path includes an absorption/diffusion member that stores therein dehumidified water.
 22. The image forming apparatus according to claim 14, wherein the imaging unit includes a photoconductor and an image transfer unit adjacent to the photoconductor.
 23. The image forming apparatus according to claim 14, wherein the imaging unit is a process cartridge in which a photoconductor and an image transfer unit adjacent to the photoconductor are integrally combined.
 24. The image forming apparatus according to claim 14, wherein the imaging unit includes transfer paper, a transfer paper transport unit, and a transfer paper container.
 25. The image forming apparatus according to claim 14, wherein the imaging unit includes a color imaging mechanism having independent photoconductors.
 26. The image forming apparatus according to claim 14, wherein the imaging unit includes a humidity detector that detects a relative humidity in the imaging unit, wherein the dehumidifier dehumidifies air in the dehumidified air flow path when the humidity detected by the humidity detector is a predetermined value or more and supplies dehumidified air to the imaging unit from the case.
 27. The image forming apparatus according to claim 18, wherein the imaging unit includes a dust-proof construction in which the dehumidified air introduced from the connecting air flow path is discharged to a downstream exhaust path.
 28. An air intake and exhaust system comprising: a flow path forming member that forms a dehumidified air flow path and an exhaust heat air flow path; a dehumidifier including a cooling-and-dehumidifying member positioned in the dehumidified air flow path, and a heat exhaust member positioned in the exhaust heat air flow path; an inlet port to which the dehumidifier is connected; a case that covers an aperture common to the dehumidified air flow path and the exhaust heat air flow path; a connecting air flow path through which dehumidified air is introduced into an imaging unit from the dehumidified air flow path; a dehumidifying fan that sends an air flow from the dehumidified air flow path to the connecting air flow path; and a heat exhaust fan that discharges exhaust heat from the exhaust heat air flow path to outside.
 29. The air intake and exhaust system according to claim 28, wherein the dehumidifier includes a water absorption member integrally provided in the dehumidified air flow path.
 30. The air intake and exhaust system according to claim 28, wherein the dehumidifier evaporates dehumidified water in the exhaust heat air flow path.
 31. The air intake and exhaust system according to claim 28, wherein the dehumidifier includes a water absorption/diffusion member integrally provided in the exhaust heat air flow path, and the dehumidifier ventilates the exhaust heat to the water absorption/diffusion member containing dehumidified water to evaporate the dehumidified water.
 32. An air intake and exhaust system comprising: a flow path forming member that forms a dehumidified air flow path and an exhaust heat air flow path; a dehumidifier including a cooling-and-dehumidifying member positioned in the dehumidified air flow path, a heat exhaust member positioned in the exhaust heat air flow path, and a Peltier element positioned between the cooling-and-dehumidifying member and the heat exhaust member; an inlet port to which the dehumidifier is connected; a case that covers an aperture common to the dehumidified air flow path and the exhaust heat air flow path; a connecting air flow path through which dehumidified air is introduced into an imaging unit from the dehumidified air flow path; a dehumidifying fan that sends an air flow from the dehumidified air flow path to the connecting air flow path; and a heat exhaust fan that discharges exhaust heat from the exhaust heat air flow path to outside.
 33. The air intake and exhaust system according to claim 32, wherein the dehumidifier includes a water absorption member integrally provided in the dehumidified air flow path.
 34. The air intake and exhaust system according to claim 32, wherein the dehumidifier evaporates dehumidified water in the exhaust heat air flow path.
 35. The air intake and exhaust system according to claim 32, wherein the dehumidifier includes a water absorption/diffusion member integrally provided in the exhaust heat air flow path, and the dehumidifier ventilates the exhaust heat to the water absorption/diffusion member containing dehumidified water to evaporate the dehumidified water.
 36. An image forming apparatus comprising: a plurality of imaging units that forms a toner image on an image carrier; a temperature/humidity detector that detects temperature and humidity in the image forming apparatus; a temperature/humidity adjusting unit that adjusts temperature and humidity in the image forming apparatus; a controller that controls the temperature/humidity adjusting unit based on a detection result of the temperature/humidity detector to adjust temperature and humidity to a predetermined range; and a heat source that generates highest temperature in the image forming apparatus, wherein the temperature/humidity detector is located near one of the imaging units located furthest from the heat source.
 37. An image forming apparatus comprising: a plurality of imaging units that forms a toner image on an image carrier; a temperature/humidity detector that detects temperature and humidity in each of the imaging units; a temperature/humidity adjusting unit that adjusts temperature and humidity in each of the imaging units; a controller that controls the temperature/humidity adjusting unit based on a detection result of the temperature/humidity detector to adjust temperature and humidity to a predetermined range; and a heat source that generates highest temperature in the image forming apparatus, wherein the temperature/humidity detector is located in one of the imaging units located furthest from the heat source.
 38. The image forming apparatus according to claim 36, wherein the temperature/humidity detector is located near or in one of the imaging units located furthest from the heat source, and not near any of the other imaging units.
 39. The image forming apparatus according to claim 37, wherein the temperature/humidity detector is located near or in one of the imaging units located furthest from the heat source, and not near any of the other imaging units.
 40. The image forming apparatus according to claim 36, wherein the imaging unit furthest from the heat source contains a black toner.
 41. The image forming apparatus according to claim 37, wherein the imaging unit furthest from the heat source contains a black toner.
 42. The image forming apparatus according to claim 36, wherein the heat source is a fixing unit that fixes the toner image on a transfer material by thermo compression bonding.
 43. The image forming apparatus according to claim 37, wherein the heat source is a fixing unit that fixes the toner image on a transfer material by thermo compression bonding.
 44. The image forming apparatus according to claim 36, wherein the temperature/humidity adjusting unit is a desiccant air conditioner.
 45. The image forming apparatus according to claim 36, wherein the temperature/humidity adjusting unit is an air conditioner using a Peltier element.
 46. The image forming apparatus according to claim 37, wherein the temperature/humidity adjusting unit is a desiccant air conditioner.
 47. The image forming apparatus according to claim 37, wherein the temperature/humidity adjusting unit is an air conditioner using a Peltier element. 